2020 BMW 840i Camshaft Replacement Cost

We recommend using the factory approved brake fluid for the vehicle being repaired, and not mixing any types of brake fluid. Also, the brake system should be flushed and inspected for obvious signs of deterioration, and repaired if necessary to prevent further failure. If the Entire brake hydraulic system is replaced, a new type of brake fluid may be used, but it must be at least the minimum standard of when the vehicle was manufactured. Also, each vehicle has a factory specified maintenance interval based upon engineering and research pertaining to the system being serviced. Following the factory scheduled maintenance interval for brake inspections and services can greatly reduce the chances of future brake system failures.

As the crankshaft turns, it uses the camshaft timing chain or belt to rotate the camshaft sprocket or gear. This assures that the camshaft will remain synchronized to the engine crankshaft at all times, thus insuring the cylinder head valves will open and close in exact synchronization with the engine's pistons. Note, the engine pistons are always in time with the engine crankshaft. As the crankshaft turns, small eccentric lobes on the crankshaft will push directly on the lifters as the peak of the lobe passes the lifter. The lifter is either directly connected to the cylinder valve, or it actuates a rocker arm. For engine camshafts mounted inside the engine block, a push rod is used to move the rocker arm, which moves the valve. Since the camshaft is connected directly to the engine crankshaft, this motion is repeated continuously, exactly, and at the proper time no matter how fast the engine is spinning.

The most common symptom of camshaft failure is a check engine light sending a code for a misfire on one or more cylinders. Also, the timing chain or timing belt may fail, which can cause catastrophic engine damage, or just require replacement. In this case, the engine will not start or run, and the engine will spin very quickly or not at all when starting is attempted. If the camshaft becomes seized due to lack of oil pressure or wear and tear, the check engine light will illuminate with misfire conditions as well as camshaft and crankshaft position sensor trouble codes. In all cases where the camshaft has failed severely enough to cause symptoms, the engine will run roughly, vibrate, hesitate, and may backfire through the exhaust, intake or both.

Camshaft failure will not allow use of the vehicle beyond the immediate future. In fact, when a camshaft fails, the engine will likely refuse to crank, start, or turn one direction by hand. If one lobe of the camshaft has become worn, the vehicle may be able to start, run and drive, but this condition will eventually lead to total engine failure as metallic debris is constantly being shaved from the crankshaft and sent through the engine oil channels. This needs to be corrected right away, as does any internal engine damage

Camshafts are not notorious for failure, but some european vehicles have been known to fail due to camshaft driven high pressure fuel pumps in as little as 20,000 miles. Besides design flaws causing issues for camshafts, the likelihood of camshaft failure for most vehicles is extremely low when the engine is properly maintained. In order to prolong the life of your engine camshaft, and all other components of the engine longblock assembly, changing the oil on time, never running low, and avoiding harsh driving should all be common practice. By following these simple rules, the engine camshaft should last the life of the vehicle.

Since the camshaft can fail by seizing or by flattening out a lobe, the technician will either receive a vehicle that runs terribly and misses on one or more cylinders repeatedly. If the engine will not crank or start, the technician will notice that the starter engaged with good battery voltage, but could not turn the engine. The engine will be turned by hand, and the technician will find they can not turn the engine. At this point, the engine is declared seized, but removal of the timing chain or belt must be done to verify if the camshaft or crankshaft has seized. If the engine cranks, but cranks quickly and without pulsation, the timing belt or chain will be inspected. If mission, the camshaft will be turned by hand, but will likely be seized. Finally, if the vehicle runs rough, the technician will begin by reading on-board diagnostic trouble codes, will find misfires on likely one cylinder, and will begin diagnostics by testing several other components. The ignition coil, spark plug, fuel injector and fuel injector seals will be tested. Afterwards, engine vacuum leak testing may even be conducted before the camshaft is suspected of failure. Once these items have been ruled out, the camshaft valve cover will be removed, and the camshaft will be directly inspected, or the lift of the rocker arms will be checked with a dial indicator. Once tested, it will be obvious that the camshaft lobe is no longer lifting the cylinder head valve enough to allow for proper operation.

For engines with the camshaft mounted internally in the engine block, either the engine will require removal, partial removal, or many components will be removed to gain adequate clearance to slide the camshaft out of the front of the engine, check the status of the camshaft bearings, and instal new components. Engines with overhead cams will require removal of the timing covers, timing adjusters, timing belt or chain, valve covers, camshaft bearing caps or girdle, and any other obstructing components. Then camshaft can be lifted out, and the bearings will be inspected, measured, and replaced if possible to ensure the new camshaft will have proper support. Finally, camshaft bearing caps or girdle will be installed with new fasteners, and the engine can be reassembled. For pushrod type engines, the pushrods and lifters must be accessed by removing the intake manifold in many cases. Also, for many engines, the rocker arms must be completely removed, and the rocker arm studs will likely be rebuilt prior to installation of the rocker arms.

Upgrading the camshaft is a common engine performance modification, so when the camshaft must be replaced, many people opt for a performance version instead of the factory version. We recommend proceeding with caution and consulting a professional concerning the size of replacement camshaft, implications on drivability, and overall performance that can be expected of different products. This will likely prevent an undesirable condition after the repair.

There are many steps to identifying a failed camshaft, and they must be followed in proper succession in order to rule out the common issues that are known to occur. However, just because a engine camshafts do not typically fail, they should not be ignored if all else proves to be in good working order. Also, note that many types of variable valve timing exist, and these are typically mounted to and adjust the position of the camshaft in relation to the engine crankshaft. This should be taken into account when the crankshaft position sensor failure OBD trouble code is stored in the powertrain or engine control module.

This job should be left to a professional. Not only does it require accurate measurements and knowledge of internal engine components and functionality, but the tooling required to properly measure camshaft clearances, lobe lift, and runout are costly. There is also a high chance of causing damage to the engine if performed incorrectly, and if the engine must be removed from the vehicle there is a chance of injury. This job should not be taken lightly, and if there is any level of doubt concerning completion of the task, consult a professional first.